Heat exchanger



Oct. 20, 1942. R. A. BOWMAN ET AL 2,299,455

HEAT EXCHANGER' 'Filed Sept. 26, 1940 INVENTQRS I ROBERT F?- BowMnN no JOBHYN F? Rn-rHsuu.

VRM

ATTORNEY Patented Oct. 20, 1942 I HEAT EXCHANGER Robert A. Bowman, Foleroft, and John 1'. Bath- Pa... assignors to Westinp house Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylbun, Prospect Park,

vania Application September 26, 1940, Serial No. 358,390

7 Claims.

This invention relates to heat exchangers, more particularly to heat exchangers wherein provision is made for sub-cooling the condensate,

and it has for an object the provision of improvedv segregate as much oi. the first pass surface as is required for sub-cooling duty, this is not satisfactory as only part of the feed water is thus utilized for sub-cooling and the rise in temperature of the feed water in the sub-cooler is thus increased, with a resultant penalty on the mean temperature diflerence between the cooling water and the condensate in this section. This, of course, increases the amount of surface required in both the sub-cooling and condensing sections.

It is submitted that the most economical arrangement is to partition oil by a longitudinal baflle all of the first tube pass and utilize the required part of this pass nearest to the inlet 4 tube plate. It is, of course, necessary to flood this sub-cooler, and since the rest of the first pass tubes which are in the condensing section must not be'flooded, means must be provided for accomplishing this double purpose.

-It is proposed to drain the condensate from the condensing section into a small hotwell provided with a suitable float control which will 9.0- tuate a valve in the condensate discharge line from the sub-cooling section. This "will result in the outlet pressure from the sub-cooling section being reduced a sufficient amount to account for the static head between the condensate level in the hotwell and the condensate water level in the sub-coolin section. Normally, this pressure differential would cause steam leakage from the condensing section into the sub-cooling section through the transverse separating baille, which would obviously defeat the purpose of the sub-cooler.

To overcome this last-mentioned difficulty, it is proposed to collect condensate on the longitudinal baflie separating the first pass tube from the remaining tubes of the heat exchanger and drain it through a port in the heme to the space between two transverse baflies positioned relatively close together. These transversely-extending baflles will constitute means for segregating the inlet portion of the first pass from the remainder oi the pass, the segregated portion constitutingthe sub-cooler section.

The draining of condensate from the longitudinal baiile to the space between the pair of transversely-extending bailles will result in distribution of this condensate around allot the tubes in the first pass, thus water-sealing the clearance holes for the tubes in the transverse'bailies, as well as any clearance space between these baiiies and the shell,

Therefore. it is an object of the present invention to provide heat exchange apparatus having 'a sub-cooling I section constituted by only the colder portion of the first tubepass.

Another object of the invention is the provision of heat exchange apparatus having a subcooling section comprised by the inlet or cold portion of the first tube pass, together with means for water-sealing the sub-cooler from the remainder of the apparatus.

' Another object of the invention is the provision of heat exchange apparatus having a subcooler together with means for maintaining the latter flooded with condensate.

These and other objects are. efiected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig.1 1 is a longitudinal sectional view through a heat exchanger embodying the principles of the invention; and,

Fig. 2 is a transverse sectional view taken along the line 11-11 of Fig. 1, looking in .the direction or the arrows. t

In the drawing there is shown heat exchange apparatus comprised by a shell ll having a steam inlet ii and a condensate outlet l2, the latter communicating with a hotwell ii. A plurality of U-tubes ll extend longitudinally of the shell and have their terminal portions, supported at one end thereof by a stationary tube plate IS, the

remaining portion of that pass by a pair of slightly-spaced, transversely-extending, vertical partitions 26 and 21. A horizontal baflle 28 extends longitudinally of the shell and separates the first pass tubes from the tubes of the remaining passes. This horizontal baffle 28 is provided with a transversely-extending slot or opening 29 overlying and aligned with the space 30 between the transversely-extending baflles 26 and 21. The horizontal bafiie is provided at its innermost free end with a transversely-extending dam member 3| and is sealed at its longitudinal edges by suitable means, such as the Lamiflex seal 32 baflie 28 with weir members 33 adjacent the opening 29 in order to maintain suficient condensate upon the baffle 28 to keep the Larnifiex seals 32 covered, thereby water-sealing the joints between the baffle 28 and the shell.

'Where the apparatus includes a desuperheating section, such as shown at, 34, there may be 1 provided an additional horizontal bailie 35 in vertically-spaced relation with respect to the bafile 28 in order to prevent fine particles of condensate lying on the bafiie 28 being picked up and deposited on the tubes of the desuperheating section by the steam flowing through the latter.

Preferably, suitable baiiles 36 extending transversely of the tubes F4, are provided throughout the apparatus to obtain maximum contact of the steam with the condensing and cooling surface. gimilarly, a baflie 31 may be provided in the path of steam entering at the inlet H to prevent erosion of tubes by impingement of high velocity steam.

The hotwell I3 is located at the condensing side of the transverse bafiles 26 and 21, but is in communication with the sub-cooler 25 through a conduit 38. In order that the sub-cooler 25 may be maintained. completely flooded at all times, there is provided an automatic float valve control comprised by a float housing 40 in communication with the bottom of the hotwell through the conduit 4| and vented to the interior of the condensing portion of the apparatus through the conduit 42. .A float 43, disposed within the housing 40, is carried at one end of the lever 44, the latter being pivoted at 45 to the housing 40 with its free end projecting outwardly of the latter. This free end is pivotally connected through the link 46 with a lever 41 pivotally mounted at 48 on the arm 49 of the valve housing 50, the latter constituting a section of the condensate discharge conduit 5|. The lever 41 is operatively connected through the valve rod 52 with a control valve (not shown) mounted in the valve housing 56.

It will be apparent from consideration of Fig. 2 'that upon increase in the amount of condensate in the hotwell l3, the float 43 in the housing 40 will be raised thereby moving the valve rod 52 to the left to open the valve in the housing 50 and permit discharge of condensate from the sub-cooling section 25, with which the condensate discharge conduit 5| communicates. The condensate discharged through the conduit 5| will be replaced by condensate from the hotwell 13 until the level in the latter has fallen enough to cause the float 43 to drop sufllciently to close the valve in the housing 56, thereby shutting ofif the discharge flow of condensate from the sub-cooler.

The last section of the condensing portion of form, it will be obvious to those skilled in the art I that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and it-is desired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What is claimed is:

1. Heat exchange apparatus comprising a horizontal shell having a steam inlet and a condensate outlet; a plurality of. tubes extending longitudinally of said shell; waterbox structure associated with said tubes and providing for circulation of water therethrough in a plurality of passes with the first pass tubes disposed in the lower part of the shell; means segregating the space within the shell surrounding the coldest portion of the first pass from the remainder of the space within the heat exchanger with the segregated portion constituting a sub-cooler, said means comprising first and second spaced, parallel, vertical bafiles extending transversely of the first pass tubes at a' material distance from the inlet ends thereof and approximately engaging at their edges with the sides and bottom of the shell, and a horizontal bafile extending from the top of said first vertical baflle to the inlet end of the exchanger in overlying relation to the tubes of the sub-cooler and having sealing engagement at its longitudinal edges with the sides of the shell; means for maintaining said horizontal baflle covered with condensate during operation of the apparatus; and means for directing the overflow of condensate from said horizontal baflle to the space between the first and second vertical baflles to maintain said space filled.

2. Heat exchange apparatus comprising a horizontal shell having a steam inlet-and a condensate outlet; a hotwell for receiving condensate end of the, shell; waterbox structure associated with said tubes and providing for circulation of water therethrough in a plurality of passes with the first pass tubes disposed in the.lower part of the shell; means segregating the coldest portion of the first pass from the remainder of the exchanger with the segregated portion constitutnig a sub-cooler, said means comprising a pair of closely-spaced, parallel, vertical baflies' extending/ transversely of the first pass between the inlet end thereof and the condensate outlet and spaced a material distance from the former and approximately engaging at their edges with the sides and bottom of the shell, ,and a horizontal baflle extending from the stationary tube plate to the nearer of said pair of baflies and having sealing engagement at its longitudinal edges with the sides of .the shell; means for maintaining a liquid seal at the edges of said horizontal baflle and said pair of vertical baflles during operation of the apparatus; and means providing for passage of condensate from the hotwell to the subcooler. v

'3. A structure as specified in claim 2, including means operable in response to change in level of condensate in the hotwell for controlling discharge of condensate from the sub-cooler.

4. Heat exchange apparatus comprising ahorizontal shell having a steam inlet and a condensate outlet; a plurality of tubes extending longitudinally of said shell; waterbox structure associated with said tubes and providing for circulation of water therethrough in a plurality of passes with the first pass tubes disposed in the lower part of the shell; means segregating the space within the shell surrounding the coldest portion of the first pass tubes from the remainder of the space within the heat exchanger with the segregated portion constituting a sub-cooler, said means comprising first and second spaced, parallel, vertical bafiles extending transversely of the first pass tubes at a material distance from the inlet ends theerof, and horizontal baflie structure extending from the tops of said vertical baflies towards both ends of the exchanger in overlying relation to the tubes of the first pass; means for maintaining said horizontal baflle structure cov-' 5. Heat exchange apparatus comprising a horizontal shell having a steam inlet and a condensate outlet; a plurality of tubes extending longitudinally of said shell; waterbox structure associated with said tubes and providing for circulation 01 water therethrough in a plurality of passes with the first pass tubes disposed in the lower part of the shell and constituting a subcooler; a horizontal baflie separating said first pass tubes from the remaining tubes and defining an opening for flow of condensate from the space above said baille to the sub-cooler; and means for maintaining the horizontal baflle covered with condensate whereby said baflle is water sealed with respect to the shell.

6. Heat exchange apparatus comprising a horizontal shell having a steam inlet and a condensate outlet; a plurality of tubes extending longitudinally of said shell; waterbox structure associated with said tubes and providing for circulation of watertherethrough in a plurality of passes with the first pass tubes disposed in the lower part of the shell and constituting a subcooler; a horizontal baflle separating said first pass tubes from the remaining tubes and defining an opening for flow of condensate from the space above said baffle to the sub-cooler; and dam means about said opening for maintaining the horizontal baflle covered with condensate whereby said baflle is water-sealed with respect to the shell.

'7. Heat exchange apparatus comprising a horizontal shell having a steam inlet and a condensate outlet; a plurality of tubes extendinglongitudinally of said shell; waterbox structure associated with said tubes and providing for circulation of water therethrough in a plurality of passes with the first pass tubes disposed in the lower part oi. the shell and constituting a subcooler; a horizontal baflle separating said first pass tubes from the remaining tubes and defining an opening for flow of condensate from the space above said baflle to the sub-cooler for counterflow through the latter; and dammeans about said opening for maintaining the horizontal baille covered with condensate whereby said baflle is water-sealed with respect to the shell. 7

ROBERT A. BOWMAN. i

JOHN P. RATHIBUN. 

